Misc.

SMS API

SMS-Pool, Secure IO, and TextVerified for phone OTPs.

For sites that text OTP codes, configure SMS providers in Settings → API keys:

ProviderNotes
SMS-PoolAPI key from your SMS-Pool account
Secure IOProvider key as shown in their dashboard
TextVerifiedOften username:apiKey format

Use SMS when IMAP email codes are not available for the account flow. Pair with Accounts and keep balance funded on the SMS provider before a drop.